Changelog

The activity link in the navigation bar now updates with the count of changes made since you last checked it

Opening of polls is now recorded in the activity stream
Article history user values now link back to that user's profile
Display name now used instead of user name in article histories
Users without javascript enabled no get a noscript message informing them about the preview &c. available on edit boxes

Some changes to the appearance/organisation of the navigation bar, should be a bit clearer
New feature: Polls and voting. Still quite early days with this, could use some testing and feedback!
You can now use @ followed by an username to link to someone's profile. @username will be replaced with their linkified display name. @puredirt -> Pure Dirt. @ can be escaped before a word, but in most cases it should be smart enough (person@example.com is seen as an email address, for example, and an @ by itself does nothing)

Previews are now available on article edit pages (still need to add to discussion pages)
There are now helper buttons at the start of edit boxes to format links, headers, etc. automatically (experimental feature -- feedback please!)
Max length of invitation codes is now a little shorter, should be easier to remember
Uploading a file now redirects you to that file's detail page
Messages are now shown on certain events. (if you've triggered some events before, you'll get a list of those messages backdated today, sorry about that!)
Some new messages in light of that, such as on registration etc.

Added a changelog
Implemented a mobile-friendly layout
"Discuss" links now show the number of comments (if any)
Sandbox now reverts automatically to blank state at 6am every morning
History no longer records the same date for every edit
Various small interface improvements
- Discussions now link back to their associated article
- As do history pages
- All pages now have title tags
- Removed some whitespace in lists/checklists
Changes to formatting of activity logs
- Humanised times (x hours ago instead of at 3:48AM etc.)
- Squash down similar items (x times instead of repeated entries)